1. Field of the Invention
The present invention relates to an Alxe2x80x94Mgxe2x80x94Si based alloy sheet that is a metal sheet suitable for an automobile body panel or the like, and that generally belongs to JIS 6000 series, and relates to an Alxe2x80x94Mgxe2x80x94Si based alloy sheet as a material suitable for an engine hood or trunk hood of an automobile, or the like, for which press-formability and in particular stretch-formability and bendability are required, or suitable for an automobile door, a fender or the like, for which deep-drawing formability is required.
2. Description of the Background
Hitherto, cold rolled steel sheets have been used as automobile panel materials. Recently, however, the use of Al alloy sheets has been increasing as the demand that automobile bodies are made lighter has been enlarging to reduce exhaust gas and cut down fuel expense. Aluminum materials that are equal to steel sheets in strength have been known. However, such aluminum materials are in general poor in press-formability such as deep-drawing formability or stretch-formability. Thus, an improvement in press-formability has been strongly demanded. Hitherto, Alxe2x80x94Mg based alloys have been mainly used as aluminum alloy sheets excellent in formability. They are poor in baking hardenability of paint and stretcher strain marks are liable to be produced when they are subjected to press forming. In recent years, therefore, attention has been paid to Alxe2x80x94Mgxe2x80x94Si based alloys of JIS 6000 series. Thus, Alxe2x80x94Mgxe2x80x94Si based alloys as follows have come to be applied to automobile body panels: a 6009 alloy, a 6010 alloy and an alloy disclosed in Japanese Published Unexamined Patent Application No. 5-295475.
Recently, it has been suggested that formability is improved by controlling structure such as texture of sheet materials and a grain size. For example, Japanese Published Unexamined Patent Application No. 5-29547 suggests an Alxe2x80x94Mgxe2x80x94Si based alloy sheet in which deep-drawing formability is improved by optimizing its texture and grain size. Japanese Published Unexamined Patent Application No. 8-325663 suggests an Alxe2x80x94Mgxe2x80x94Si based alloy sheet excellent in press-formability wherein the ratios of respective orientation components are controlled.
However, it cannot be said that these Alxe2x80x94Mgxe2x80x94Si based alloy sheets have sufficient formability. Thus, automobile makers demand a further improvement in formability.
In the light of such a situation, the present invention has been made. An object thereof is to provide an Alxe2x80x94Mgxe2x80x94Si based alloy sheet whose press-formability (particularly, deep-drawing formability, stretch-formability and bendability) is made higher than conventional Alxe2x80x94Mgxe2x80x94Si based alloy sheets of JIS 6000 series.